Fix typo in gdb-goto-first-gdb-instance.

Fix typo in gdb-goto-first-gdb-instance.

Re-write gdb-look-for-tagged-buffer to avoid recursion (I was getting
errors because of too much nesting, obviously elisp lacks tail
recursion optimization)

Fix toggle-bp-this-line for new ways of communicating with gdb and
rename to gdb-toggle-bp-this-line.